Steady-state corona charging behavior of a corotron over a moving dielectric substrate

Charging up a dielectric surface through corona discharge from a thin wire has been a common practice in electrophotographic processes. One of the widely used corona charging devices is called a corotron and consists of a coronating wire enclosed in a shield with one constituent side being the surface to be charged. Uniform surface charge can be created on a dielectric substrate such as photoreceptor by moving the substrate at a constant velocity through a stationary corotron that steadily emits corona ions. To design efficient corotron for charging dielectric substrates, fundamental understanding of the electrostatic nature of the device is desired. In the present work, the steady-state behavior of corona charging with a corotron over a moving dielectric substrate is analyzed by computationally solving nonlinearly coupled equation system with Galerkin finite-element method and Newton iterations. The predictions based on a first-principle model are shown to agree well with experimental measurements.